Fixed Pros: Indirect Restorations/Crowns

Question 1

Briefly describe indirect restorations.

Answer 1

A restoration that needs to be fabricated extra-orally prior to placement intraorally. The restoration is constructed on an accurate model of the dental arches.

Question 2

What are the materials you can use for indirect restorations?

Answer 2

• composite resin
• alloys and ceramics
• gold

Question 3

What are the advantages of indirect restorations?

Answer 3

• No plastic phase/no need to pack and cure
• Fabricated under lab conditions/no need to work inside mouth
• Improved aesthetics e.g.: ceramics)
• Can more predictably manage advanced cases

Question 4

What are the disadvantages of indirect restorations?

Answer 4

• More visits required (at least 2)

- Needs careful planning and skilled execution

Question 5

What are the indications for indirect restorations?

Answer 5

• teeth vulnerable to further breakdown
• heavily restored teeth
• reorganise the occlusal scheme during rehab
• an option for fixed replacement of missing teeth
• extensively restored abutment for a Co/Cr RPD
• Aesthetic reasons

Question 6

List the types of indirect restorations.

Answer 6

• Inlay
• Onlay
• 3/4 crown
• 7/8 crown
• full coverage crown
• bridge pontic
• veneer
• implant supported-crown and bridge

Question 7

What is an inlay?

Answer 7

A dental restoration made outside of the tooth to conform to the prepared cavity, which is then luted into the tooth. Does not involve the cusps.

Question 8

What materials can you use for an inlay?

Answer 8

CR, gold alloys, ceramics

Question 9

What are the requirements for an inlay?

Answer 9

• rounded line and point angles
• NO UNDERCUTS
• prep floor is flat or concave
• slightly divergent axial walls
• 6 degrees of taper
• PM’s should have 1 intact marginal ridge, M’s may be MOD design
• for small to moderate-sized lesions

Question 10

What is an onlay?

Answer 10

An indirect restoration that restores one+ cusps joined to occlusal surfaces or the entire O surface.

Question 11

What are the advantages of onlays?

Answer 11

• provides cuspal protection after RCT

- less expensive than full coverage crowns

Question 12

If you’re making an olay and using ceramics, what do you need to keep in mind?

Answer 12

• Ceramics are brittle. They need minimum 1.5mm thickness, which means the preparation needs to be more aggressive.

Question 13

What are the materials you can use for onlays?

Answer 13

CR, ceramics, metal alloys

Question 14

What are metal-ceramic combos used for in indirect restorations?

Answer 14

Crowns and fixed partial dentures.

Question 15

What are the advantages of using metal ceramics?

Answer 15

• Very strong and durable
• Wear resistance is high
• the metal part of the material has high fracture resistance

Question 16

What are the disadvantages of using metal-ceramic materials?

Answer 16

• Cavity prep is moderately aggressive
• Multiple appts required - Wear resistance is high but this may wear the opposing teeth
• ceramic fractures on impact
• there may be sensitivity to the base metal
• cost is higher

Question 17

What are the advantages of using ceramics?

Answer 17

• good aesthetics
• is biocompatible and usually well-tolerated
• generally high wear resistance

Question 18

What are the disadvantages of using ceramics?

Answer 18

• Is brittle and can fracture under heavy loads
• Multiple appts needed
• Wear resistance is high but may wear opposing teeth
• higher cost

Question 19

What are the advantages of using cast-gold?

Answer 19

• high corrosion resistance
• least amount of TS removed
• high fracture and wear resistance
• is biocompatible; allergies rare

Question 20

What are the disadvantages of using cast gold?

Answer 20

• aesthetics (not suited for anterior teeth)